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Another Take on Subject-Line Length
Repost: Original article by:magillreport
Yeah, yeah. First I say the subject-line-length debate is a waste of time. Then I devote half a newsletter to it.
Well, even though I do think the entire debate’s a waste, that doesn’t mean no one had anything interesting to say.
Dela Quist, CEO of email marketing agency Alchemy Worx, had a lot to say. And if you want to get your geek on, he’s your guy.
Here’s Quist’s take on subject-line length:
Let me start by saying that John Forman [of MailChimp] whether he knows it or not is basically agreeing with my central premise, which is that anyone who thinks that there is there is a “best” or “optimal” subject-line length; be that long, short or in between is deluded and any discussions around that as are as useful as a discussion around the best length for a piece of rope.
In fact as I have said before the reason we decided to do the research in the first place was because I was fed up with the industries blind adherence to the “shorter is better” doctrine prevalent at that time, which was fuelled research by MailerMailer.
I have to confess that I was expecting to find what John @ MailChimp thinks he has found which is that there is “on the whole, not only no causation, but even no correlation.”
I assumed that their findings were unique and a result of the composition of the MailerMailer client base, they define a large list as 10,000 (I think) but subsequently found that not to be the case.
So what we found not only surprised and delighted me (I love a bit of serendipity) it laid the foundation for a lot of our thinking around subject lines and how to use them to the best effect.
Basically we found that open rates – assuming you care about them – tend to fall as the SL length increases while click rates tend to rise. For a full explanation of the phenomenon and why we think this happens I do recommend that you read (or re-read) the original white paper, which is free to download here .
Now does that mean that every short subject line will beat the open rate of every long subject line – NO and only a fool would suggest that – but what it does mean (and all the studies including MailChimp’s show this) is that:
– More opens do not guarantee more clicks. There are times where the 2 lines are moving in opposite directions
– There are times when shorter is better and others where longer is better
There are times when a longer piece of rope is better; when marking out a 400 meter running track and times when shorter is better; when tethering a vicious dog. Our white paper seeks to show you how and when to use each.
So why the difference in findings?
In a word -Methodology.
MailerMailer, Alchemy Worx and Adestra all used the same method of calculation. We all calculated the average open and click rate for each group, i.e. we took all the subject lines that fell into the 11-20 character range and calculated the average open and click rates for that group. We then did the same for 21-30 etc. etc.
MailChimp and the research presented by Jordie [van Rijn, marketing consultant] on the other hand used a completely different approach and one that I am less than comfortable with.
First of all they calculated the average open rate for every single subject line of all lengths and calculated the average, they then went on to calculate how much the average for each group deviated from the average of all emails
Now I unlike John am not a mathematician so I am prepared to be shot down in flames, but I think that is why both charts show such high deviations from the average for both very short and very long SL’s. The vast majority of SL’s fall is between 30 to 90 characters in length, so the sample size at either end is very much smaller and prone to greater deviations from the mean.
However because the average is very heavily weighted towards the middle of the range there is much less deviation from the mean.
The other thing to bear in mind when looking at any subject-line-length research is that the data is somewhat biased in favour of shorter subject lines because we tend to use shorter subject lines for our strongest offers. Think, “Free shipping ends tonight”, “Warehouse Blowout”, “48 Hour Sale” etc. So it is no surprise that short or very short SL’s <35 characters perform so well.
When we did our research I made sure that we sanity checked our findings by using the MailerMailer approach on our data too. Guess what? We found that we were able to replicate their results.
If we cut our subject-line data in two defining short as 34 characters or less and long as 35 + characters, we also found shorter to be better for both opens and clicks (but not necessarily if you made the cut elsewhere). MailerMailer subsequently used our approach and ended up with similar results to ours and the Adestra findings.
» Read the Original and Complete Article
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